Billionaire Peter Thiel's $1.25 million backing of Donald Trump's presidential campaign has caused rifts in Silicon Valley.

Over the weekend, news broke that Thiel — co-founder of PayPal and chairman of start-up Palantir — had donated $1.25 million in support of Trump.



Thiel already voiced his support for Trump at the Republican National Convention. But his donation is an outlier in the tech world, which had donated around $8 million to the campaign of Democratic presidential candidate Hillary Clinton, versus $300,000 to her rival, according to Recode, citing Crowdpac data.

Thiel is a part-time partner at Y Combinator, a major Silicon Valley start-up accelerator run by Sam Altman, who tweeted on Sunday that Trump's views are an "unacceptable threat to America." But Altman added that he would not fire Thiel because it's a "dangerous path to start down."

Altman's comments about Thiel drew the ire of Ellen Pao, co-founder of Project Include, a company working to help tech organizations become more diverse. Pao was the former chief executive of Reddit — the site that bills itself as the "front page of the internet." Last year, Pao was locked in a discrimination lawsuit against her former employer, venture capital firm Kleiner Perkins Caufield & Byers, which she subsequently lost.

In a blog post on Monday, Pao hit out at Altman's decision not to fire Thiel, as well as the latter's support for Trump.

"While all of us believe in the ideas of free speech and open platforms, we draw a line here. We agree that people shouldn't be fired for their political views, but this isn't a disagreement on tax policy, this is advocating hatred and violence," Pao wrote.